Safety switch



E. L. MASON Sept. 29, 1936.

SAFETY SWITCH Filed Nov. 10, 1933 Ear/M A. MAJOA ATTO RN EYxS Patented Sept. 29, 1936 UNITED STATES PATENT OFFICE 1 Claim.

This invention relates to safety switches and is characterized by its ability to break an electrical circuit under a given set of conditions and maintain the circuit against re-establishment except by special manual manipulation.

When a vehicle, such as an automobile, accidentally overturns fire very often results because of failure of the driver to cut off the ignition. Furthermore, if a driver meets with an accident involving considerable tilting or overturning without any burning it is often necessary for him to abandon his car temporarily to seek assistance and such cars are sometimes stolen. It is therefore an object of this invention to provide a switch which will not only cut oif the ignition upon abnormal tilting thereof but which will not establish the circuit by simply righting the switch.

More specifically it is the object of this invention to provide a mercury contact switch with a catch basin for the mercury upon abnormal tilting, the basin being capable of emptying only upon manipulation in a particular manner not expected to be encountered in any accident, as for instance by manipulation requiring overturning of the car at slow speed about some axis transverse of its length.

Other objects and advantages will become hereinafter more fully apparent by reference to the accompanying drawing wherein my invention is illustrated by way of example in several modifications and in which Figure 1 is a diagrammatic illustration of an automobile having my invention installed thereon;

Fig. 2 is an enlarged view of my improved switch mounted on a panel;

Fig. 3 is a vertical section along the line 33 of Fig. 2 showing particularly the retaining means;

Fig. 4 is a view on a smaller scale of my improved switch;

Figs. 5, 6, and 7 are views of the switch of Fig. 4 showing various positions thereof.

More particularly, l refers generally to a vehicle such as an automobile having electrical wiring 2 as for an ignition circuit, the main line of which is connected to a panel 3 by terminals 4 and 5. The terminals are each connected to electrodes 6 of a switch 1 forming the subject matter of this invention. This switch is composed of a U-shaped tubular body, the upper ends 8 of which are reversely bent for termination in spherical bulbs 9. The electrodes are bridged by a quantity of mercury ID. The switch is demountably secured to the panel 3 by any suitable means such as the spring clips H. A tube I2 connects the top portions of the tubes 8n for the purpose as more fully hereinafter stated.

If the vehicle turns on its side, for instance, or assumes any accidentally abnormal angle likely 5 to cause incapacity of the occupants the mercury ID will flow and break the electrical circuit. Sufficient tilting will cause the mercury to flow into one or the other of the bulbs 9 where it will remain when the car is righted either of its own 10 accord or by a person. The only maner in which the mercury may be caused to flow to its normal circuit closing position is by dismounting of the tube from its clips and subsequent rotation or tilting in a manner which the vehicle would never 15 be expected to follow while the switch is mounted in its panel.

If desired, the clips H may be of a type rendering dismounting more diflicult in order that a greater amount of time would be consumed by some attempting to re-establish the circuit in the owners absence.

The switch illustrated in Figs. 4 to '7 is the same as that above described except for showing the action of a connecting tube portion l2, the tubular portion la and the bulbs 9a being the same. This additional connection I2 joining the top portions 8a is a means for causing the circuit to remain broken in case of complete overturning or rolling over of the vehicle. When upside down as shown in Fig. 5 the mercury is almost wholly within the portion l2. If the rotation of the vehicle is clockwise, as viewed in Fig. 1, the mercury will assume the position shown in Fig. 6 when again on its side and if the car then finds an upright position the mercury will remain in the left bulb as shown in Fig. 7.

Various small changes may be made without departing from the spirit of my invention and I therefore desire to be extended protection as defined by the appended claim.

What I claim is:

A mercury switch comprising a U-tube having electrodes near the base thereof, mercury in said tube normally bridging said electrodes, the top of the U -tube being reversely bent and terminating in spherical bulbs having greater diameter than the remainder of said tube, said bulbs comprising catch-basins for retaining the mercury flowing thereinto upon abnormal tilting of said tube, and a tubular connection between the outer ends of said U-tube comprising an additional catch basin.

EDWIN L. MASON. 

